Richard Frank and his wife Tammi have been trying to track down the grave of Mrs Frank’s baby sister Jane, who died in June 1963.

Jane – who was just 30 days old when she died – is believed to have been buried at Royston Cemetery according to data from Hertfordshire Records and Archives.

But the records do not reveal the exact location of her grave so the couple have spent the last two years trying to find the missing information.

Mr and Mrs Frank have said a book containing plans of the graveyard, which would reveal Jane’s burial site, was taken by the vicar at the time when he retired.

The couple, of Woolgrove Road in Hitchin, met Archdeacon of Hertford Trevor Jones on Thursday for a private meeting, held within the graveyard area.

After the meeting, they said: “In spite of giving the Archdeacon information he asked for to help him with his enquiries, he has only made peripheral enquiries. The meeting was full of broken promises.

“The book is church property containing official records that would be to the advantage of the church if it was returned.

“The Archdeacon’s offer to place a memorial was not appropriate. The area in which he offered had one infant’s grave dated in the 1880s.

“There are other areas with a number of infants’ graves that would have been far more suitable.”

The couple said they still want the church to carry out an investigation to find the grave by gathering information from local undertakers, gravediggers and other locals who may have had any involvement in the funeral.

The Diocese of St Albans said: “The Archdeacon of Hertford has done all he can to help locate this grave, but he regrets there is no more he or anyone can do that is likely to throw any further light on the precise location of the grave after exhaustive and comprehensive enquiries.

“He equally regrets that Mr and Mrs Frank have refused the offer of a headstone memorial to Jane in the churchyard.

The diocese said there was no obligation on the vicar or parish, more than 50 years ago, to mark the exact place of burial.